Both the opposition and the ruling party in Bosnia's autonomous Serbian region, the Republika Srpska, have called on supporters to take to the streets of the capital, Banja Luka, for demonstrations ahead of local elections in October.

The opposition will protest against unemployment and corruption, while the ruling party urged people to express support for government policies.

Vucic said Serbian intelligence had seen indications the protests could turn violent. He said he had spoken to Bosnian Serb leaders, including the republic's president, Milorad Dodik.

"We don't need conflict," Vucic told a news conference on May 11. "Peace and stability are conditions without which Serbia cannot progress."

Dodik has repeatedly tried and failed to persuade opposition leaders to cancel the protests, but says he does not envisage any problems with having two rival protest meetings on the same day.

Vucic's remarks reflect pressure that Belgrade feels from the West to support stability in the Balkans if it wants to make progress in talks on joining the European Union.